Cylinder-piston motor with means for stopping relative movements of the motor parts



s. w. e. BEARD CYLINDER-PISTON MOTOR WITH MEANS FOR STOPPING RELATIVE MOVEMENT OF THE MOTOR PARTS Filed Feb. 13, 1947 Kb N 2 Sheets-Sheet 11 Feb, 20, 1951 s w G. BEARD 2,542,463

CYLINDER-PISTON MOTbR WITH MEANS FOR STOPPING RELATIVE MOVEMENT OF THE MOTOR PARTS Filed Feb. 13, 1947 2 Sheets-Sheet 2 Patented Feb. 20, 1951 TCYLINDER PISTON MOTOR 'WITH "MEANS FOR STOPPING RELATIVE MOVEMENTS OF -THE- MOTOR PARTS l Samuel William George. :Beard, Gloucester,. Eng- .land, .assignor to RotoLLimited, Gl0.uceste "England, a British company Application February 13, 1947; SerialNo;*7 28340 Infireat' Britain J anuary 11,..1 9 46 Section. 1; Public Law 69'0,'A 11sti8,.'.19$6 'Patentexpires January; .115; 1966 A .Claims'. 1 This invention relates to-cylinderpiston motors and more particularly to r a: mechanical device for stopping the relatively movable parts of the motor "in-a predeterminedintermediate position. The 'invention is also applicable to the motors incorporated-in hydraulically operated variable pitch propellers.

It is often desirable in hydrauliccylinder-piston motors to providean intermediate stop position within the range of movement-of the piston and. to :permit movement of the a piston beyond thispcsitionronly under predetermined circumstances. For examplain' hydraulically operated 'variable pitch .propellersrwhereinthe pitch range :of the :blade is .su'fficient to permit operation -,under reverse zthrust :conditions, it :is not only desirable but essential under 'normaheon'ditions .th'at. blades ishall only changez pitch between :a normally'fine setting .and .awcoarser setting, the blades-onlyv being permitted to .move belowthe .fine pitch setting toreverse :thrust .when. a deliberate action is'made.

Themain object ofthe present invention is .to provide simple and efficient means for ensuring :such intermediate: action inf acylinder-piston motor.

In order that the invention may be clearly un- .,derstood -a: practical emhodim-entwillznow be described, by way'of example, with referenceto the accompanying drawingsrwhereof,

Figure-1 is asectional elevation of-.a-hydraulio jack of a variablepitch propellerinaccordance with the present invention,

1 Figure 12 -is.a' similar view tWFigure 1-: and showing amodifiedconstructiomand Figurefi is-a sectionakeevation of a part of the mechanism .of' Figure 1. and to an --enlarged ,scale zto show. certain. details of-construction.

Referring to Figure 1 z the .hub of the ;,pr.o-

"peller is indicated at fiandthis hasysecuredto it a. cylinder :6 within which. slides .a piston l coupled to the blades ofthe propeller through links Bin-known manner. The cylinder and pis .tonassembly forma hydraulic motor foralteringthe pitch of .the blades, andthev travel ofthe piston! is of such an extent that the blades can be turned from the feathered toa reversed pitch position. ;In ,the arrangement shown the piston -'l .travels to .theleftuto turnethe blades towards vreverse pitchand to therightto turn the blades .to the coarsepitch. or feathered position.

Thepiston'l is anannular piston .andslideson an annular guide Swhich is attached to the hub 5- of the propeller, as at 40. The piston I has an. annular extension Ill .which will behereinafter termed the ffbuiieresleeveff "To the interior of-the free end of the annular "guide Sthere is securedan annularsleeve-like member II which is slottedaxially' (see the lower half of thedrawing) "to provide-a plurality of resilient tongues or struts, this slotted sleeve constituting what will hereinafter be'termed a radially resilient abutment. The Tree BIiClSJOf the tongues zarethickened to form abutment shoulders l2 andtheir external diameter is chosen so that in the normal position ofthe abutments the buffer-sleeve H3 will engage therewith. The a'djacent faces of the abutment shoulders-Hand the. buffer sleeve in .arechamfered :asxshown at site.

Within;the-resilient abutment II there isgarranged-a movable cylindrical member i4 which is guided on an annularguide l5. Betweenthe-rear wall It. of this-.;plug:..andr a fixed. member l1 dis.- posed ;,centr ally within :the cylinder 6*thereris arranged aspiring; H3. The. latter tendsto: push the cylindrical member. .I 4" towards the left in Fig- ;ure; 1. The cylindricalmember I4 is formed-with an external: ring i9 whose diameter is chosen so that it is a sliding fit within the abutment-shoulders l2, and in the position of the plugrshownzih Figure-J, the -tonsues of therresilient abutment are prevented from: collapsing radiallyxinwards by the-ring I9.

The annular "guide lfi'is associatedwithpiston members 29 between which and correspondingly formed members'on' the cylindrical'member 1M there is defined thespaces :2]. :zThelatter-zare in communication; witha duct1z22 through holes .23 in the; guide 1 15. The guide 15;;is supported upon a central tube '24 having :,a:ra:dial ho-le25 which-places the'duct 221incommunicationwith the interior of a piston valve 29 mounted therein. 'JIhe; latter. is urged by-a spring 2'! towards the right-so that/the. hole. 2 5, ispp nto the interior-pf .the valve. 3 ilIhe central space.;28 within the :cylindrical member [4 communicates withtheleithandisiide oi thecylinder Gby-meansofa hole 29in the annular wall of the cylindrical member. The 'main operatingpressure-fluid for 'the pitch-adjustingjack is conveyed thereto by' a :nested pair, of-tubes-3fl,- 3|, the space between the ztubescommunicating by a duct 32iwith-ther1fi ht hand end of the cylinder 6. Thus, when-pressure .fluid; passes into the space between the tubes :30, 3] alongv duct 32 and to the. right ihanid-endzof the cylinder ,6, the piston l 'ismoved towards the left to turn the blades towards reverse pitch. The interior of tube 3I communicates with a space-3'3 which is itself .in communication with thelef t e -d;-s sl qieib -r li dewli e henrnressure-fluid is directed along tube 3| it enters space 33 and the left hand end or the cylinder so that the piston I is moved to the right to turn the blades of the propeller to the coarse pitch or feathered position. As stated above this pressure-fluid will also be in communication with the space 28 through the hole 29.

By arranging pressure-fluid to be delivered to one side of the piston 1 whilst fluid from the other side is open to exhaust the piston can be caused to move axially and thereby vary the pitch of the blades as indicated.

The axial position of the resilient abutment is determined by the flange 34 which is integrally formed with the cylinder 6. The length of flange 34 is so chosen that when the buffer-sleeve l engages the abutment shoulders l2 the blades of the propeller are in a predetermined position, namely, the fine pitch position. With the normal working pressure of the hydraulic fluid supplied to the piston 1 to efiect such engagement of the buffer sleeve and abutment shoulders, the valve 26 will be held in its extreme right hand position by spring 27. When the blades reach their fine pitch position further movement is prevented by the engagement of the buffer sleeve with the abutment shoulders H, the tongues being prevented from inward radial collapse by the ring IQ of member 4. The piston I may therefore not move further to the left and the propeller blades are held in the fine pitch position.

When it is desired that the piston 1 move further to the left to turn the blade to a reverse pitch position, fluid at a pressure higher-thannormal is supplied to the right hand end of the cylinder 6 by way of duct 32 as described above.

--It will be observed that the duct 32 also communicates with the valve 26 by way of channel 35 and that the pressure of the fluid passing to the right hand end of the cylinder 6 is applied to the valve 26 to urge it towards the left i. e. against spring 2'1. Accordingly when the higher-thannormal pressure acts on the piston I its application to valve 26 moves the latter towards the left,

spring 21 being designed to allow this. The valve will therefore be opened and permit the application of this pressure to the spaces 2|, the fluid passing thereto by hole 25, duct 22 and holes 23. The member I4 is thereby moved against the effort of its spring is to withdraw ring Hi from under the abutment shoulders |2.

As a consequence the tongues of the resilient abutment H are free to move radially inwards. The higherthan-normal pressure is also acting on the piston 1 and causing the buiier sleeve ID to press against abutment shoulders i2 and the piston i to move further to the left in Figure 1.

In this way the blades are rotated to a reverse pitch position. This movement is terminated by the engagement of the piston i with a stop 35 formed on the wall of cylinder 6.

Upon reversal of the pressure fluid supplied to the hydraulic motor (which may be still at higher-than-normal pressure) so as to cause piston '5 to move to the right, this fluid is no longer applied to the valve 26 and it is therefore returned by spring 21 to the position shown. Consequently the-spaces 2| are placed in communicationby 2,542,463 .1. "TI f f 441.

holes 23, duct 22 and hole 25 with the left hand end of the cylinder 6. As has been stated above space 28 is permanently in communication with the left hand end so that the hydraulic pressures on each side of the member l4 are equal and the spring |8 is thereby enabled to return the member M to its initial position where the ring l9 lies under the abutment shoulders I2. This will occur consequent upon the piston I being moved towards the right so that the buffer sleeve I0 is clear of the abutment shoulders. The ring H! ha sloping sides so as radially to push the tongues of the resilient abutment outwardly when the member I4 is being returned to its normal position.

In the modification shown in Figure 2 like parts to Figure 1 are indicated by like numerals. It

will be observed that the construction of Figure 2 is generally the same as Figure 1, but in this case the member M ha a piston member l6 which is slidable within a cylindrical wall 37 which is attachedto the cylinder 6 of the hydraulic jack at the front end thereof. The member I4 is guided by annular guide |5. The passage of higherthan-normal pressure fluid to the space 2| is regulated by the valve 26 in the same way as described above. When this pressure is applied to the hydraulic jack it acts upon the valve to open it and as a result the pressure fluid is admitted to the space 2| to move the member l4 towards the right. The ring I9, is therefore, moved towards the right to disengage the abutment shoulders l2 for the purpose indicated: the

propeller blades will then be moved to the reverse pitch position. When it is desired to un-reverse the propeller blades pressure fluid is admitted to the left hand end of the cylinder 6 to move the piston I to the right and at the same time the higher-than-normal pressure will be disconnected from the valve 26. The latter will be returned by its spring 2'! so as to place the pace 2| in communication with the left hand end of the cylinder 6. The pressure on each side of the piston member of member I4 will therefore be balanced and it Will be moved by its spring ill to bring the ring l5 under the abutment shoulders |2.

I claim: 1. A cylinder-piston motor comprising a stop to prevent relative movement between the piston and the cylinder intermediate the limits of stroke of the motor, resilient means urging the stop in a transverse direction out of the path of the movable part of the motor, a second piston means for normally holding the stop in said operative po: sition, spring means to maintain said second piston in its normal holding position and valve means for applying the working pressure of the motor to the second piston to move said second piston to disengage the stop when said pressure becomes higher-than-normal upon engagement of the movable part of the motor with the stop.

2. A cylinder-piston motor comprising a stop to prevent relative movement between the piston and the cylinder intermediate the limits Of stroke of the motor, resilient means urging the stop in n? a transverse direction out of the path of the movsaid greater pressure is applied to the second ton to move it to disengage the stop.-

3. A cylinder-piston motor comprising a stop to prevent relative movement between the piston and the cylinder intermediate the limits of stroke of the motor, resilient means urging the stop in a transverse direction out of the path of the movable part of the motor, a second piston means for normally holding the stop in said operative position, spring means to maintain said second piston in its normal holding position, a two-p0- sition valve arranged so that in one position the working fluid is applied to the second piston and in the other position the pressure fluid on the second piston is released, and spring means normally holding the valve in its second position, the valve being moved to its first position when the working pressure is greater-than-normal whereby said greater pressure is applied to the second piston to move it to disengage the stop.

4. A cylinder-piston motor as claimed in claim 3 wherein the stop comprises a set of radiallyresilient, circularly disposed abutments against which a buffer sleeve, carried by the movable part of the motor, is adapted to abut.

SAMUEL WILLIAM GEORGE BEARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Oct. T12, 1938 

